This invention relates to a brace used to conservatively correct the hallux from valgus.
"Hallux valgus" denotes a state or symptom of the hallux crooked toward the second toe. It had been attributed to the use of inadequate shoes (particularly shoes with pointed toes). At present, however, inadequate shoes are considered not the primary cause, although it may be a significant factor for worsening the deformation or the symptom. The primary causes are tumefaction of the head of first metatersal, abnormal first tarsometatarsal joint, abnormal muscular abductor pollicis or musculus adductor pollicis, abnormal joint between the first metatersal head and sesamoid, longer and larger first metatersal than second metatersal, and reluxed ligament. In any case, the first metatersal is excessively bent inward and then bent outward at the metatarsophalangeal joint, and the hallux is bent outward and intensely twisted relative to the other four toes, thus appearing in many cases to be opposite to them. When the deformation is noticeable, the inside of the first metatersal head grows larger and with a formation of bursa orcallus results in further enlarged projection. This bone projection and bursa together are commonly called a "bunion". Oppression and rubbing by shoes on this part can cause decubitus or bursitis and in some periosteomylitis circumscriptus.
In Europe and America wherein more cases are found than in Japan, a large variety of methods of operation have been disclosed (conventional methods of correcting a bunion include cutting off the head of first metatersal, a combination of osteotomy and tendotomy, new joint formation by implanting, etc.). The many different approaches to correcting the bunion shows that no single method is available that gives excellent results.
Surgical operation of a hallux valgus accompanied by congential arthrochalasis or nervimuscular disease is said to have a relapse rate of 50% or more. In such a case, operation should be avoided.
In addition, such a high degree of deformation as requiring osteotomy of the first metatersal is rare, and in Japan where the operation is not well developed, conservative treatment is almost always chosen as the method of treatment.
However, the conventional "brace remedy" has a number of drawbacks. The feet are an only region of the body that contact the ground when standing or walking. Thus, a brace should naturally not hinder such action. Two methods available for hallux valgus correction are pressing the hallux from the second-toe side or pulling it from the opposite side, but either of them is difficult to perform effectively in daily life such as wearing shoes or sandals, walking with it put on, and repeating putting it on and off. Thus, the patient prefers to avoid braces which are, for example, rigid, bulky, or troublesome to handle even if prescribed. As the last resort to make up such drawback, the manufacturers have provided two types of brace for selection by patients; a "waking brace" which cannot be expected to have sufficient effect and a "night brace" which is effective but not suitable to walking since it is rigid and bulky.
It has been a common practice to manufacture braces one by one according to the size and condition of individual patient particularly for braces made of metal. Consequently, the cost has been very high.